WO-A-2016046487, for example, describes a wall structure for creating the flat wall of a tank with double sealed membrane. The secondary sealed membrane of such a tank wall experiences high stresses in service, these being associated with the various loadings of the tank, with thermal contraction, with movements of the cargo, and with deformation of the bearing structure in the swell. These stresses are notably transmitted by the thermally insulating barrier to which the secondary sealed membrane is anchored. Because the thermally insulating barrier is made up of large sized discrete insulating panels, the stresses and movements transmitted to the secondary sealed membrane are not distributed uniformly which means that the corrugations in the secondary sealed membrane are stressed differently according to whether they are situated near the edges of the panels or near the center. In addition, the flexibility of certain corrugations is limited by the anchoring of the edges of the metal sheets to the panels. This results in stress concentrations liable to accelerate the aging of the sealed membrane. These problems would also exist if the primary membrane were eliminated.
In WO-A-2016046487, bridging elements arranged between the secondary insulating panels serve to improve the distribution of the movements by limiting the separation movements of the edges of the panels. These bridging elements are able to a certain extent to address the separation movements of the edges of the panels but are limited, complicated to install, and have a relatively high installation cost.